import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class code1 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char[] s = in.next().toCharArray();
        boolean[] hash = new boolean[10];

        for(int i=s.length-1;i>=0;i--) {
            char x = s[i];
            if(!hash[x]) {
                System.out.print(x);
                hash[x] = true;
            }
        }
    }
}